Libor (London interbank offered rate), is meant to represent how much banks pay to borrow from one another. It is also a benchmark for at least US$550 trillion worth of contracts spanning interest rate derivatives to residential mortgages. A scandal erupted after banks were found to be rigging the system. Barclays was fined US$453 million by global regulators in June 2012 for manipulating Libor, and UBS was hit with a US$1.5 billion bill in December 2012. In February 2013, RBS was fined US$612 million to settle US and UK regulatory charges of misconduct, manipulation, attempted manipulation and false reporting of yen, Swiss franc and dollar-denominated Libor.

Britain's leading prosecutor, the Serious Fraud Office, is poised to charge more individuals in connection with a global investigation into the Libor interest-rate-rigging scandal.

To date, US and British authorities have charged seven men and fined four financial firms about US$2.7 billion in the investigation into the manipulation of the London interbank offered rate (Libor), used as a benchmark for more than US$300 trillion of products from derivatives to home loans.

David Green, who has led the fraud office since April last year, said the inquiry into Libor, a central cog in the global financial system, remained the largest and most complex case on his books - and he expected to be judged by its results.

"I anticipate there will be further [Libor] charges this autumn," Green said. "Thereafter, there will be further significant developments … We're not finished by a long chalk."

He said relations with the US Department of Justice, which has had a near three-year head start in the Libor investigation, were "genuinely helpful and constructive".

Although the justice department has been first to charge some British suspects in the scandal, Green said everyone understood that they should be tried in Britain rather than extradited to the United States.

"So far as I'm concerned, alleged crimes committed by British suspects or banks should be tried here and that is the goal to which we would work," he said.

Green declined to divulge whether further Libor charges would be announced before a London court hearing later this month, at which a list of alleged co-conspirators of former UBS and Citigroup trader Tom Hayes and two former brokers will be read out.

Hayes, who has also been charged by the US, and former RP Martin brokers Terry Farr and James Gilmour are the first individuals to be brought to court over a scandal that has become a symbol for the financial industry's self-serving excesses.

US prosecutors have also charged Swiss-based former UBS trader Roger Darin and three former staff at interdealer broker ICAP - New Zealand-based Darrell Read, his British-based supervisor Daniel Wilkinson and cash broker Colin Goodman.

Libor and similar benchmarks are designed to reflect each bank's own borrowing costs. But traders allegedly encouraged bank submissions that benefited their trading positions.

This article appeared in the South China Morning Post print edition as More to be charged over Libor scandal